Wireless network technologies may sometimes use signals to help determine radio link characteristics between two devices. In an example, a cellular radio network may assign a signal, such as a sounding reference signal (SRS), to a user equipment (UE) to use in link estimations.
In an example, a network according to a 3rd Generation Partnership Project (3GPP) family of standards (e.g., 3GPP Long Term Evolution release 10, 3GPP standard 36.21X vb.x.x, release 11 and beyond), may use a number of orthogonal base sequences as SRSs. In an example, the network may use Zadoff-Chu base sequences because they provide a constant amplitude electromagnetic signal in radio communications and are also orthogonal when cyclically shifted. A cyclic shift is generally a set number of translations of the underlying base sequences. For example, given a sequence {a, b, c, d} a cyclic shift of two would yield the sequence {c, d, a, b}. These qualities provide for robust link quality estimations and allow different sequences to be assigned to different UEs in order to distinguish between the UEs. In 3GPP Long Term Evolution (LTE) compliant networks, cyclic extensions of Zadoff-Chu base sequences may be used to align the base sequence to the physical link characteristics, such as SRS resource block (RB) allocations. Such cyclic extension reduces the orthogonality property of the sequences. In this case, the orthogonality of the sequences may be said to be quasi-orthogonal. However, as used herein, the definition of orthogonal sequences includes quasi-orthogonal sequences (i.e., the terms may be used interchangeably).
In an example, some wireless networks may use coordinated multipoint (CoMP) reception to enhance performance. CoMP may involve the use of two or more wireless network devices to receive a wireless signal and coordinate the received signals to increase data integrity. To improve the effectiveness of CoMP some wireless networks may increase signaling from a transmitter (e.g., a UE) in order to facilitate coordination of received signals. In an example, such as the Long Term Evolution (LTE) release 10 3GPP standard, the increased signaling may be accomplished via more frequent sounding, for example, in either a periodic or an aperiodic fashion.